Core B The Recombinant Technologies Core (Core B) is designed to fulfill critical gaps in core support for projects related to developmental neurobiology. Specifically, this core along with Core C has been designed to serve as a cost-effective, intellectual and technical focal point for the bench scientists who address issues of nervous system development and function that are germane or directly related to MRDD. The need to introduce genetic material into their experimental neural or glial preparations is a strategy common to these investigators. The Recombinant Technology Facility provides state-of-the-art technical and personnel support for researchers interested in the expression and deletion of genes and other molecules in a variety of cells and tissues. Such methods are crucial for understanding the mechanisms underlying neural development. Through these services, the Core facilitates studies at the molecular level of brain development and function and disease processes, by promoting collaborative projects among MRRC investigators and by enabling investigators to combine newly acquired cellular and molecular tools with other approaches, such as electrophysiology and behavior. The advantages of the Recombinant Technologies Core include shared technical expertise, cost savings, and interactive discussion on the roles of classes of molecules in development that an individual investigator might not otherwise have appreciated or been able to evaluate.